Most experiments that claim to show the quantum Zeno paradox fall short, study says

Jun 05, 2013 by Lisa Zyga feature

(Phys.org) —By their very nature, unstable particles will eventually decay, some faster than others. But according to the quantum Zeno paradox (QZP), an unstable particle that is observed continuously has been said to never decay. Though counterintuitive, this effect has been claimed to show up experimentally in numerous ways. Now in a new study, physicist Peter Toschek at the University of Hamburg in Hamburg, Germany, has argued that most of these experiments do not provide sufficient evidence of the QZP. By identifying the sufficient conditions necessary for proving the QZP, he confirms the validity of the paradox while probing deeper into its origins.

Toschek's paper, "The quantum Zeno paradox: A matter of information," is published in a recent issue of EPL.

"The QZP holds for all unstable whose transition (or 'decay') is electromagnetically induced," Toschek told Phys.org.
.
As he explained, most experiments that have claimed to prove the QZP (or its manifestation, the quantum Zeno effect) rely on measurements of "expectation values," which are group averages that don't provide information on individual objects, in particular on their survival times. Instead, he explains that the outcomes of should represent "eigenvalues," which do provide information on individual . He explains that the survival time of a particle can be derived from uninterrupted sequences of the detected eigenvalue of the initial, undecayed state of the quantum system (particle plus radiation field), provided an individual quantum object is addressed.

For example, in some experiments that use light-irradiated atoms to demonstrate the QZP, a continuous measurement has been approximated by a series of short irradiating a group of 5,000 unstable atoms. Then the mean of the atoms has been measured. The results of these experiments show that the mean decay rate decreases when the pulse repetition rate increases, and this finding has been interpreted as evidence of the QZP.

In these experiments, the measurement of the average decay rate of the entire group of atoms generates an expectation value, a classical quantity with a deterministic result—apart from small fluctuations from "projection noise." In contrast, quantum measurements are known to show conditionally random results.

In order to come up with eigenvalues instead of expectation values, Toschek explains that measurements of the decay process should be characterized by individual survival times. Importantly, this condition lies in the definition of the QZP. Further, the effects of each light pulse on the atom should be recorded. In this way, the information on the state of the atom gained by a measurement affects the prediction of the average of results. The results of classical measurements (like those measuring the mean decay rate) are insufficient to demonstrate the QZP because they are indistinguishable from results of other effects, such as spectral line-broadening by radiative saturation of an atomic resonance line.

"So far, wide-spread misconception has claimed the QZP to be the cause of simple phenomena (for example, the 'power broadening' of irradiated atoms), which involve neither quantum measurements nor the Zeno effect (extension of the survival time under measurement)," Toschek said.

While most of the claims for demonstration of the QZP have fallen short of satisfying both the criteria for being "quantum" and "Zeno," a few experiments have met all the requirements and provide sufficient evidence to support the existence of the QZP. So the results of the current paper don't question the validity of the paradox. Rather, they distinguish it from well-understood and unsurprising effects and present an explanation of the paradoxical aspects in terms of the transfer of quantum information.

Explore further: Mapping the optimal route between two quantum states

More information: Peter E. Toschek. "The quantum Zeno paradox: A matter of information." EPL, 102 (2013) 20005. DOI: 10.1209/0295-5075/102/20005

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julianpenrod
1.4 / 5 (11) Jun 05, 2013
So often, fundamental facts fail to enter "scientific" "analyses", invalidating them. Fortunately for the liars, many if not most are unaware of these facts to challenge the lies. For example, the "quantum Zeno paradox" claims that, if impacted by a swift progression of electromagnetic pulses for the purpose of measurement, an unstable system will change its characteristics and not, on average, decay when it should. A problem with this is that it ignores that all systems, under the "official" "scientific" definition of the universe, are constantly being bombarded by electromagnetic pulses, photons at least in the long radio range, from everywhere! So all systems must automatically already not be abiding by supposedly normal decay rates. Claiming the effect does not exist, however, as this article does, might run afoul of the report that everything from solar flares to the rotation of the sun's core to the time of the year can alter decay rates of radioisotopes.
Noumenon
1.6 / 5 (27) Jun 05, 2013
if impacted by a swift progression of electromagnetic pulses for the purpose of measurement, an unstable system will change its characteristics and not, on average, decay when it should.

A problem with this is that it ignores that all systems, under the "official" "scientific" definition of the universe, are constantly being bombarded


The error in your analysis is that you appear to be equating Measurement and (unobserved)-Interaction. The nature of that relationship is not entirely understood.

For example, the 'wave-function' is unobservable in itself and does NOT 'collapse' upon a (unobserved)-Interaction. It may become entangled and may be subject to decoherence, but does not collapse to a 'value'.

In contrast, in order for "it" to become observable, it must take on a conceptual value or form. It gets 'projected' (collapses) onto a axis basis of the particular 'representation' determined by the measurement apparatus.
Noumenon
1.6 / 5 (28) Jun 05, 2013
In principal, you could arrange a quantum wave-function state that includes the quantum system plus experimental apparatus plus human observer, all described quantum mechanically. Fine, but then this complex system can no longer constitute a measurement as a wave-function alone is not observable and is not itself a measurement, since it is a superposition of all possible states,... not a singular conceptual Value. Another observer would be required.
julianpenrod
1.5 / 5 (8) Jun 05, 2013
The limited length of the comment permitted did not allow me to include my reference to interaction and what is being referred to as "measurement". But, in fact, "science" precludes that sentience be considered as anything different from "inanimate" existence. A system supposedly should not perceive that a sentient being is observing it. In a more general, sense, though, all interaction is measurement. How else does a gravitating particle know how to respond gravitationally, it can be said, than by measurement? How else would a particle react electrostatically except by measuring the charge of a nearby particle? But, then, to contradict someone not in favor, "science" devotees, it seems, will even resort to violating "science" tenets themselves.
Noumenon
1.6 / 5 (28) Jun 05, 2013
science" precludes that sentience be considered as anything different from "inanimate" existence.


Yes, I expect that consciousness should have a physical basis and in principal should be able to be described by a 'wave-function' of all its possible states of all its components, as I mentioned.

A system supposedly should not perceive that a sentient being is observing it.


I agree. As far as the system is concerned it is interacting with another system. There is no mystical component to sentience as far as i'm concerned.

What makes an observation distinct from a physical interaction, is the imposition of conceptual form,... the expectation of measurable values. The 'underlying reality' is not made of numbers and concepts.
Protoplasmix
1 / 5 (2) Jun 05, 2013
Each observation adds some energy to the system, effectively resetting the internal decay countdown clock, so to speak, to some random value. An excessively energetic observation, like probing a radionuclide with a fast neutron as opposed to an xray photon, would trigger a decay. If that's correct, where's the paradox?
beleg
1 / 5 (3) Jun 05, 2013
"What makes an observation distinct from a physical interaction, is the imposition of conceptual form,... the expectation of measurable values. The 'underlying reality' is not made of numbers and concepts." - N

The limits of your world are the limits of your language.
Either your quoted statement is an assumption of a void...void of anything, or assumes realism.

There are no true paradoxes. All paradoxes come to being when the limits of the language used to word them is reached.

DavidW
1.5 / 5 (8) Jun 06, 2013
A system supposedly should not perceive that a sentient being is observing it.


I regard consciousness as fundamental. I regard matter as derivative from consciousness. We cannot get behind consciousness. Everything that we talk about, everything that we regard as existing, postulates consciousness.
Max Planck
antialias_physorg
3.7 / 5 (3) Jun 06, 2013
The 'underlying reality' is not made of numbers and concepts.

Good point.
the influence ofthe interpretative layer is certainly an iffy one. However, we've tried to measure in various ways and unless there is some fundamental/interpretative issue (i.e. something so innate in the mind of all people(!) that we can't even become aware of it*) it seems that interpretation doesn't play a crucial role.

* and seeing as the mind has had a pretty good run of being able to notice stuff/think around stuff such a premise seems far fetched. I don't buy Hoffstadters argument about the record player that can't play all records.

Then again: a watched pot never boils - proof of the QZP (just kidding)
thingumbobesquire
1 / 5 (2) Jun 06, 2013
Thought isn't a form of energy. So how on Earth can it change material processes? That question has still not been answered.
Vernadsky
antialias_physorg
3.7 / 5 (3) Jun 06, 2013
Thought isn't a form of energy. So how on Earth can it change material processes?That question has still not been answered.

Neural activity seems to correlate pretty well with thought (and especially the absence of neural activity seems to be 100% correlated with an absence of thought).

So there is energy involved when thinking. Or what did you think your brain uses all those nutrients for you have to keep feeding it?

There. Answered it for you.
thingumbobesquire
1 / 5 (2) Jun 06, 2013
Neural activity is thought? I think not...
antialias_physorg
3.7 / 5 (3) Jun 06, 2013
Neural activity is thought? I think not...

...because? Don't leave us hanging here.
You've stated an opinion and now you should support it with data (or at least a line of reasoning).Just saying: "It ain't so, and science has got it all wrong for the past 100 years." isn't enough.
beleg
1 / 5 (2) Jun 06, 2013
Max Planck's statement is at odds with Noumenon's statement.
I assert Max Planck's statement cited here and quoted is a translation from a statement Max Planck originally stated in German. The person who quoted Max Planck can clarify and put to rest the notion or assertion that Max Planck statement has been translated.
Noumenon
1.3 / 5 (25) Jun 06, 2013
However, we've tried to measure in various ways and unless there is some fundamental/interpretative issue (i.e. something so innate in the mind of all people(!) that we can't even become aware of it*) it seems that interpretation doesn't play a crucial role.


The act of measurement is itself an interpretation. Conceptualization (necessarily innate to all minds in acquiring knowledge) of Reality is itself an interpretation. QM is a theory of observer experience, not of observer-independent reality. [to reject Realism]. The results of observations are described by classical information.

The Schrodinger wavefunction doesn't represent a physical entity itself, but instead our knowledge of a system, or as Einstein put it ... "just a peculiar statistical device for observers .....who are ignorant of the values of the hidden variables underneath". Except, "the ignorance" comes from our concepts failing to span the underlying reality, "the underneath".
Noumenon
1.3 / 5 (26) Jun 06, 2013
Thought isn't a form of energy. So how on Earth can it change material processes? That question has still not been answered.
Vernadsky


Imo, it's not that thought as a physical system causes some physical effect upon an independent physical system,... rather it is, that what we mean by "a physical system", is only ever existent in thought to begin with. IOW, a physical system as we describe it, does not exist independently of us. [this is not to deny an Independent Reality; it is to regard knowledge of Independent Reality as metaphysical non-sense (as in Realism)].

When we perform a measurement on this 'physical system as knowledge', it changes, because our knowledge changes then.
Noumenon
1.3 / 5 (26) Jun 06, 2013
"What makes an observation distinct from a physical interaction, is the imposition of conceptual form,... the expectation of measurable values. The 'underlying reality' is not made of numbers and concepts." - N

The limits of your world are the limits of your language.
Either your quoted statement is an assumption of a void...void of anything, or assumes realism.


What do you mean, 'assumption of a void'.
beleg
1 / 5 (3) Jun 06, 2013
If Max Planck's statement is to hold, then taking away consciousness takes away matter.
A field-less, virtual particle-less, matter-less space is a void. A perfect "underlying" "reality".
Exempt from science. Failing the null hypothesis - the accessibility to method.
Failing philosophy. UN-contemplationable. Figuratively 'drawing' a 'blank'.
Realism fails here too. - Independence of everything invites meaninglessness to any inquiry or question.
Protoplasmix
1 / 5 (3) Jun 06, 2013
How does all that emerge from a void? Imo, a more perfect [sic] underlying reality has all possibilities in superposition, ever ready with an answer or resolution in resonant accord with all possible inquiries or measurements. The inherent properties of resolution invoke truth, specifically numbers, maths, and fundamental principles, these things being more concrete and stable than the derived quanta themselves.
beleg
1 / 5 (4) Jun 06, 2013
All our thoughts are maps to reality, aside from if reality is "underlying".
The Schrodinger equation is a map asserting whatever detail the territory (reality) harbors or whatever detail is revealed, you can add the missing detail to your map.
The equation is all accommodating, like your mind.
The assumption is there is no cover to hid variables.
Only your search to find them is insufficient.
You don't start over. You evolve.
Zeno's paradox is not a paradox.
At this temporary stage of time in the search to complete your map your language short changes you not your map.
Noumenon
1.3 / 5 (26) Jun 06, 2013
If Max Planck's statement is to hold, then taking away consciousness takes away matter.
A field-less, virtual particle-less, matter-less space is a void. [....] Independence of everything invites meaninglessness to any inquiry or question.


I don't know the context of Planck's statement, but taken at face value and associating with my statements above,... he nor I, in anyway promote idealism. There are rational reasons for believing in a independent objective reality (see my screen name), albeit unknowable as it is in itself.

What is being stated is merely a truism, that knowledge of reality implies consciousness and all the necessary a-priori conceptual baggage that entails. We can acquire knowledge only of 'empirical reality', ... reality as experienced, ..not independent of mind.

Taking away consciousness would leave Independent Reality just as it always existed, ..unconceptualized.
Noumenon
1.3 / 5 (26) Jun 06, 2013
Btw, the phrase 'underlying reality' is used by those Realists who think that QM is incomplete. That the theory is missing some aspect of reality ((non-local) hidden variables). Any theory that is incomplete, would imply the notion of an 'underlying reality' that is not fully describe by it.

I'm merely taken this to its logical anti-Realist conclusion,... that since knowledge is conceptualized and obviously mind dependent, there must be a 'underlying reality' that isn't, and thus is unknowable in principal. This is no way invalidates scientific knowledge of empirical reality.
beleg
1 / 5 (3) Jun 07, 2013
Those "realists" are mistaken. The assumption is the state vector is complete.

"'underlying reality' is used by those Realists who think that QM is incomplete. "-N
The rest of your comment expounds on this.
Protoplasmix
1 / 5 (2) Jun 07, 2013
I doubt the amount of void between my ears has any effect on the inner, fundamental, or underlying workings of reality. Like (or with) time, reality marches on just fine with or without me and my observations. If I should wish to fill the void with understanding, the correct answers already exist and are spoken in the language of maths. Despite the physical limitations with regard to observations at the smallest scales, if I discover enough correct maths I can use it to predict demonstrable things, as Dirac did with antimatter.
beleg
1 / 5 (3) Jun 08, 2013
A continuum (of space) exists until you introduce what you label "a point" to that continuum.
From that point on (double pun intended) all is discrete.
Where limits exist.. (Calculus)
For all practical intentions and purposes the continuum (hypothesis) acts as an "underlying reality" for diehard philosophers.
ValeriaT
1 / 5 (5) Jun 08, 2013
The Zeno paradox is the consequence of fact, that the observer is usually larger, heavier and as such more stable, than the effect observed. When you observe some unstable artifact, you're becoming entangled with object observed and you're permanently pumping an energy into it during process of observation and thus making it more stable. From the same reason the popular stars struggle to remain in public attention of scandal sheets, as it makes their existence more reliable due the various synergies.
Protoplasmix
1 / 5 (2) Jun 08, 2013
Correct me if I'm wrong - observations of the cross sections suggest a point-like nature, and the only other point I'd introduce is the one that says the laws of physics are the same in my lab as they are in any other lab.
drhoo
not rated yet Jun 10, 2013
Life itself is an organizing function, taking raw materials and building complexity. Especially among us humans, as not only do we grow physically, we grow mentally, taking in observations and forming predictive machines ( our brains ).

The universe is ultimately a large computer, it is now in its infant phase with intelligent life life evolving all over and eventually unifying in a universal gaia.

Yes antialiasphysorg this is unsupported speculation, but then again don't all ideas start that way.
beleg
1 / 5 (3) Jun 11, 2013
Whatever exists before becoming a 'collapsed state' excludes any definition called self-organization. A complete state needs no evolution. What do you add to a complete state?
Only 'collapsed states' harbor 'limited' information to do, expereince or exhibit 'ordinary' (classic) events - life, decay, death, physics, science, thought, evolution, experience, motion, time...(the list as long as your vocabulary and imagination).
There is not the least objection from me to label uncollapsed states a computer or intelligence. The additional meanings to those labels from uncollapsed states will escape the comprehension of any life or intelligence existing in a collapsed state.
beleg
1 / 5 (3) Jun 11, 2013
Bear with me for a two sentence hypothetical:

1.)Biology/Chemical physics just solved the 'life from a test-tube' and proclaim:
"This sample and the evolutionary control sample are indistinguishable!"

2.)The information theorists reply:
"Yes, they are physically indistinguishable. No measurement will ever tell them apart."
One lacks evolution and the other sample does not.

And declare the samples nonequivalent quantum (informational) states.
There is no loss of information. There is lack of information.

Or is evolution time, place and scale invariant?